What are your favorite, "under the radar" or lesser-known films?

I've always loved movies, I just didn't realize how much til recently. In college when friends would come over they would often comment on how many movies I owned, and I didn't think much of it. But, I've only been 'into' films in the last year or two, so I'm still quite unfamiliar with lesser know/under the radar films. I was hoping some people that know their stuff better than me would recommend some their favorite lesser known yet good quality movies. I just recently watched Attack the Block with John Boyega, I wasn't expecting much since I'd only heard of it from Boyega's wikipedia page. Attack the Block blew my mind, I loved it SO much, so good I almost couldn't believe I hadn't heard of it before. After some looking around, it seems I'm not alone with loving this movie, it just happens to be a lesser known movie. Got me thinking, what other awesome movies are out there that I've never even heard of?!